.traffic-light{
  .light{
    display: inline-block;
    background: url(//lh3.googleusercontent.com/-YWLqWZXDYHU/VmWC7GHoAuI/AAAAAAAACgk/nXvEmSWAhQU/s800/light.png) no-repeat 0 0;
    background-size: auto 100%;
    overflow: hidden;
    width:140px / 2;
    height:328px / 2;

    &.red{
      background-position: 0,0;
    }
    &.yellow{
      background-position: -78px , 0;
    }
    &.green{
      background-position: -156px , 0;
    }
  }
}